[Mne_analysis] continuation (from Fieldtrip list) of writing fifs

[Eric Larson]

Hey Andy,

Yes, it should be possible to implement a precision argument in mne-python.
I should be able to get to it this week.

Cheers,
Eric



On Wed, Jan 30, 2013 at 6:38 AM, Dykstra, Andrew <
Andrew.Dykstra at med.uni-heidelberg.de> wrote:

> Hi Alexandre, Peter,
>
> While it's not nearly as problematic as going from 2 to 18 Gb, I also
> experience file size increases (usually exact doubling minus the last
> small buffer) when rewriting fif files, not only in MATLAB but also with
> the Python tools.  In my case, I've always wondered whether it's just a
> difference in the default writing precisions between the modern MNE
> package and our system (Neuromag 122), in which case I'm content with
> storing the data in the higher precision.  In any case, would it be
> possible to include a precision argument in the Python writing tool?
>
> Cheers,
> Andy
>
> --
> Andrew R. Dykstra, PhD
> Auditory Cognition Lab
> Neurologie und Poliklinik
> Universitätsklinikum Heidelberg
> Im Neuenheimer Feld 400
> 69120 Heidelberg
>
> "How small the cosmos.  How paltry and puny compared to human
> consciousness . . . to a single individual recollection." - Vladimir Nabokov
>
>
>
> "hi Peter,
>
> > The size of the input file is ~2gb but when
> > writing, the output is approx ~18gb. I suspect I'm writing a WHOLE bunch
> of
> > redundant data, but am unable to open the new file, even on a machine
> > running 16gb RAM.
>
> what is likely to happen is that the matlab code writes data as double
> precision
> while the original neuromag data were in float 16. Note that a single fif
> file
> cannot exceed 2Go due to internal pointer arithmetic otherwise it will
> be broken.
> What you can do is hack the fif writing to make sure it's written back
> in float16.
>
> Best,
> Alex
>
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